Last week initial XWayland support was merged into the X.Org server code-base. As explained in a few Phoronix articles already, it uses a new design of XWayland as a DDX with GLAMOR for 2D acceleration instead of XWayland being a module and requiring modifications to the hardware DDX drivers.
With the XWayland DDX code being merged for the X.Org Server 1.16 release due to happen this summer, Kristian Høgsberg has gone ahead and made the modifications to the Weston compositor for supporting the new XWayland DDX design. With just over 100 lines of changed code, per this commit, the mainline X.Org Server XWayland code now works with Weston.
So for released package versions, end-users will be looking forward to the X.Org Server 1.16 release that is set to occur around July and the Wayland/Weston 1.5 release that will likely take place in about one month's time.